In many situations, it is desirable to determine the distance from one point to another, for example, to locate an object. It is possible to determine a distance between two points by using radio frequency (RF) waves. Some methods of distance determination involve using a first device to transmit an RF signal to a second device, and determining the distance between them by analyzing the attenuation that has occurred during the propagation of the signal.
Other methods of distance determination involve determining the time of flight of a signal that is transmitted from a first device to a second device and then using the equation:d=c×ttof  (1)
where d=the distance between the first and second devices, c is the speed of light and ttof is the time of flight.
In order to make estimate the distance as accurate as possible, the time of flight should be determined with as little error as possible.